Murfreesboro is a city in Pike County, Arkansas, United States. The population was 1,764 at the 2000 census. The city is the county seat of Pike County. Crater of Diamonds State Park is located just to the south. The crater is an eroded lamproite pipe where diamonds were discovered in 1906. 100,000 were found by 1933, and visitors to the park may still take away whatever they can find.
The guard cells surround each stoma in a plant cell. They regulate  the opening and closing of stomata to facilitate gas exchange and  control transpiration in plants.
All Answers (17) The opening and the closing of the stomata depend upon the necessity of the plant to lose water and heat through transpiration (exit of water vapor means elimination of heat). When the plant has excessive water the guard cells become turgid and the ostiole opens. When little water is available the guard cells become flaccid and the ostiole closes. Water enters and goes out the stomata by osmosis. Other factors like light intensity and carbon dioxide concentration in the leaves influence the opening and the closing of the stomata.